JPH025426B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to medical tubes. More specifically, the present invention relates to improvements in tubes used in various medical devices. Prior art and its problems Traditionally, medical tubes made of soft polyvinyl chloride have been widely used, and are used for infusions, transfusion vessels,
It is used in various medical devices such as artificial kidney circuits and catheters. This is because soft polyvinyl chloride has excellent processability and adhesive properties, is easy to handle when assembling medical devices, and can be mixed with a plasticizer arbitrarily, making it easy to adjust flexibility. However, if soft polyvinyl chloride contains a plasticizer and is used in a medical tube, there is a risk that the plasticizer will elute and migrate into blood, medical solutions, and the like. Conventionally, a technique is known in which a polyvinyl chloride sheet is subjected to plasma treatment in order to prevent plasticizer migration. However, such techniques cannot be practically applied to the inner surface of the tube. Therefore, the material forming the medical tube must be changed to one that does not contain plasticizers. In this case, excellent materials such as silicone tubes are known as materials that are highly flexible and do not require plasticizers. However, none of these materials can be extruded, resulting in high costs when formed into a tubular shape. Furthermore, they cannot be bonded with adhesives or high-frequency melting, and cannot be subjected to secondary processing, making them difficult to manufacture into various medical devices. Extremely difficult to assemble. In addition, it is expensive. On the other hand, tubes made of various olefin polymers are also known, but when used as medical tubes, they still lack adhesive properties and
It has poor flexibility and cannot be bent easily, and the tube itself may break when bent, resulting in blockage of liquid or the like. Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to improve the characteristics of conventional medical tubes made of flexible polyvinyl chloride, particularly flexibility, workability, adhesiveness, etc. The object of the present invention is to provide a medical tube that is equivalent to or better than that and is free from eluates. More specifically, it does not contain additives such as plasticizers, has no eluates, has excellent flexibility, has very little tube bending, has excellent recovery properties after deformation, can be extruded, and has good adhesive properties. It is an object of the present invention to provide a medical tube having extremely good properties overall, such as excellent secondary processability and good transparency. The inventors of the present invention have repeatedly and diligently researched for this purpose, and as a result, they have arrived at the present invention. That is, in the present invention, the chlorine content is 25 to 45 by weight.
% chlorinated polyethylene, low density polyethylene, styrene-butadiene random copolymer, styrene-butadiene block copolymer, styrene-butadiene teleblock copolymer, and ethylene-vinyl acetate copolymer with a vinyl acetate content of 30 wt% or less A medical tube formed by molding a blended polymer with at least one thermoplastic resin selected from the above into a tubular shape, wherein the thermoplastic resin is blended in an amount of 10 to 50 parts by weight per 100 parts by weight of chlorinated polyethylene. , contains virtually no additives, and has an initial elastic modulus of 5Kg/mm ²
The medical tube is characterized in that the curvature at which bending occurs at 0° C. does not change compared to room temperature. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. The medical tube of the present invention is made of a polymer blend of chlorinated polyethylene and other thermoplastic resins. The chlorinated polyethylene used in the blend is particularly medium-density to high-density polyethylene that has been chlorinated according to a conventional method. Chlorine is bonded randomly on the polyethylene chain, and the degree of chlorination, that is, the chlorine content, is , in terms of weight ratio, is 25 to 45%, more preferably 30 to 40%. With such a chlorine content, compared to soft polyvinyl chloride, flexibility is further improved, tube bending is significantly reduced, and recovery after deformation is significantly improved. Furthermore, the flexibility and impact resistance at low temperatures are significantly improved compared to soft polyvinyl chloride. The molecular weight of the chlorinated polyethylene used is not particularly limited, but a number average molecular weight of approximately 40,000 to 300,000 may be used. Moreover, there is no particular restriction on its distribution. Further, the density may normally be about 1.00 to 1.25. On the other hand, various thermoplastic resins other than chlorinated polyethylene can be used for blending.
Seeds or more can be used. Among these, polyolefins, olefin copolymers, and styrene copolymers are particularly suitable as the other thermoplastic resins referred to herein. this is,
This is because when one or more of these is blended with the chlorinated polyethylene, extremely favorable properties can be obtained in terms of flexibility and transparency. Among these resins, particularly preferred specific examples include the following. (A) Low-density polyethylene, especially linear low-density polyethylene (LLDPE). Particularly preferred are those having a density of 0.915 to 0.940 and a melt index of 5 g/10 minutes or less based on ASTM D-1238. (B) Ethylene-vinyl acetate copolymer (EVA) Vinyl acetate (VA) content 30wt% or less, especially 5-25wt%, density 0.915-0.95, number average molecular weight 50,000-200,000, melt index 7g/10 Particularly preferred are those of less than 1 minute. (C) Styrene copolymer, especially styrene-butadiene copolymer 1 Styrene-butadiene random copolymer (SBR) Styrene content of about 20-40%, number average molecular weight of about 200,000, Mooney viscosity of about 20-60 is particularly preferred. 2. Styrene-butadiene block copolymer (SB) A soft segment consisting of polybutadiene and polyisoprene, which is block copolymerized with the polybutadiene and a polystyrene hard segment present at the end. In this case, it is preferable to have a density of 0.94 to 0.95 and a melt index of 5 g/10 minutes or less. 3 Styrene-butadiene teleblock copolymer (SBS) A soft segment consisting of polybutadiene, polyisoprene and polyolefin, block copolymerized with these, and polystyrene hard segments present at both ends. In this case, density 0.90 ~
0.94, a melt index of 10 g/10 minutes or less is preferred. The thermoplastic resin other than the chlorinated polyethylene to be blended preferably has a refractive index of about 1.48 to 1.52 from the viewpoint of transparency of the blended polymer. The blending ratio of such chlorinated polyethylene and other thermoplastic resin is preferably 10 to 50 parts by weight of the thermoplastic resin per 100 parts by weight of the chlorinated polyethylene. When the amount is 10 to 50 parts by weight, flexibility and low-temperature properties will be good. In this case, the blending ratio is 100% chlorinated polyethylene
per part by weight, 1 to 100 parts by weight, more preferably
When the amount is 10 to 50 parts by weight, the flexibility and low-temperature properties become even better. Then, they are blended according to a conventional method at such a blending ratio to form a blended polymer. A blended polymer made of such chlorinated polyethylene and other thermoplastic resin is molded into a tubular tube. In this case, the initial elastic modulus of the molded tube is 5 Kg/mm ² or less. Here, the initial elastic modulus G is determined by JIS K 7113 at the rising edge of the deformation-stress curve in the small deformation range.
Accordingly, G = W・l/△l・A [where W is the applied load (Kg), l is the initial length (mm), △l is the elongation (mm), and A is the cross-sectional area (mm ² ) ]. And when the initial elastic modulus is 5Kg/ ^mm2 or less,
Flexibility is greatly improved, tube bending is reduced, and recovery is improved. In addition, low-temperature properties, especially flexibility and impact resistance at low temperatures, are improved. In this case, it is preferable that the initial elastic modulus is in the range of 0.1 to 4.0 Kg/mm ² from the viewpoint of flexibility and the like. In addition, in order to adjust the initial elastic modulus to 5 kg/mm2 or ^less , the conditions can be easily adjusted by changing the chlorine content, molecular weight, crystallinity of chlorinated polyethylene, or the type and blending ratio of other thermoplastic resins. It can be determined experimentally. Furthermore, from the viewpoint of transparency, the tube preferably has an absorbance of 0.18 to 0.65 at 500 nm per 1 mm thickness. On the other hand, during molding, there is no need to add additives such as plasticizers to the blended polymer.
Therefore, there is almost no elution from the inner wall of the tube. On the other hand, shaping can be carried out by conventional extrusion processing. Therefore, the molding process becomes extremely easy and the cost becomes low. In this case, production becomes easier if dry blending is performed using a screw in an extruder. The tube formed in this way usually has an inner diameter of about 1 to 20 mm and a wall thickness of about 0.3 to 3.5 mm. In addition, it exhibits extremely good flexibility in such dimensions. Note that its cross-sectional shape, dimensions, etc. can be varied. Such medical tubes of the present invention can be used for connection tubes such as infusion sets and blood transfusion sets, tubes for body fluids or blood circuits in various extracorporeal circulation circuits such as dialysis machines and artificial kidneys, tubes for various indwelling needles, various catheters, etc. Furthermore, it is used as a tube for a breathing circuit, etc. These various medical devices are assembled by high-frequency bonding the medical tube of the present invention to other components in a predetermined arrangement, or by performing other desired secondary processing. Specific Effects of the Invention The medical tube of the present invention is made of a blend polymer of chlorinated polyethylene and other thermoplastic resin, and unlike polyvinyl chloride, it does not require the addition of additives such as plasticizers. Very little elution into body fluids, blood, drug solutions, etc. It also exhibits better flexibility than soft polyvinyl chloride. That is, tube bending is extremely rare, and the bending radius of curvature at which tube bending occurs is extremely small compared to polyvinyl chloride. Also,
Restoration properties against deformation are also good; for example, when an incision is caused by a crevice, it restores immediately after the incision is removed, and it also has good followability and resistance to incision, and is more stable than polyvinyl chloride. Excellent flowability. Furthermore, when stored at low temperatures for a long period of time or at low temperatures, polyvinyl chloride loses its flexibility, but the tube of the present invention has less bending and has good constant flow properties. It also has high impact resistance. Such flexibility and low-temperature properties are better than that of chlorinated polyethylene alone. In addition, when performing ethylene oxide gas sterilization as a sterilization process, the degassing rate of the ethylene oxide gas adsorbed after sterilization is lower than that of soft polyvinyl chloride because it does not contain additives such as plasticizers. fast. Furthermore, it is resistant to γ-ray sterilization, and its physical properties remain unchanged. In addition, extrusion processing can be performed well, manufacturing is easy, high-frequency dielectric heating and adhesive bonding are possible, and bonding processing is easy.In addition, various secondary processing when assembling into medical devices is possible. can also be easily done. If chlorinated polyethylene with a chlorine content of 30 to 40% is used, the above flexibility will be even better. The refractive index of the other thermoplastic resin to be blended is
Since the absorbance of the tube at 500 nm is 0.18 to 0.65 per 1 mm thickness, the tube has good transparency when handled as a blood tube. Furthermore, when the tube inner diameter is 2 to 15 mm, the effect of improving bending and constant flow properties is remarkable. In order to confirm the effects of the present invention, the present inventors
Various experiments were conducted. An example is shown below. Experimental Example 1 High-density polyethylene with a number average molecular weight of 100,000 and a density of 0.95 was chlorinated to obtain chlorinated polyethylene (PE-Cl) with a chlorine content of 30% and a density of 1.13. On the other hand, as other thermoplastic resins, the above-mentioned SBS
(Soft segment: polybutadiene, polyisoprene, polyolefin, hard segment: polystyrene, density 0.93, melt index 10
g/10 minutes), the PE-Cl to SBS weight ratio was 80:20, and the mixture was put into the hopper of the extrusion machine and extruded in the screw cylinder.
After blending at 130-190℃, the temperature is 190℃ from the die.
The tube of the present invention was produced by extruding it into a continuous tube having an inner diameter of 3 mm and an outer diameter of 4 mm. Separately, a tube with the same dimensions was similarly prepared from PE-Cl alone. Furthermore, from soft polyvinyl chloride (PVC; Nippon Zeon Co., Ltd. 103EP) containing plasticizers and stabilizers,
Tubes with the same dimensions were also produced by extrusion. In addition, ethylene with a vinyl acetate content of 15wt%
Vinyl acetate copolymer (EVA; manufactured by Toyo Soda Kogyo Co., Ltd.)
Similarly, a tube with the same dimensions was made from UE-630). The initial elastic modulus G of these four types of tubes was measured according to JIS K 7113. The results are shown in Table 1. In addition, in Table 1, the 500 nm wavelength of four types of tubes is
The absorbance of 1 mm thickness is shown.

[Table] Furthermore, eluate tests for these four tubes were conducted. In other words, take 15g of the tube, cut it into small pieces, boil it in about 150ml of water for 30 minutes, then add water to make 150ml.
This was used as the test solution. To 10 ml of this test solution, add 20 ml of 0.01N potassium permanganate solution and 1.0 ml of dilute sulfuric acid, boil for 3 minutes, cool, add 0.1 g of potassium iodide and 5 drops of starch test solution, and add 0.01N sodium thiosulfate. Titrated with liquid. The amount of reducing substances eluted (△
KMnO ₄ ) is shown in Table 2. In addition, when KCl was added to the test solution and PH was measured according to the pharmacopoeia, the difference (△PH) from the blank shown in Table 2 was obtained. Furthermore, these 0.5 m tubes were made into a loop shape, filled with bovine blood, and shaken for 1 hour to perform a hemolysis test. The occurrence of hemolysis is indicated by + and - in the table.

[Table] From the results shown in Table 2, it can be seen that the tube of the present invention has an extremely small amount of hemolysis. Separately, the following flexibility test was conducted. First, four types of tubes were wound around cylinders having various diameters, and the radius of curvature at which bending occurred was measured. Table 3 shows the measurement results at 0°C and 20°C. Further, the tube was made 1 m long, a chamber and a bottle needle were attached to one end, a needle was attached to the other end via a rubber tube and an octopus tube, and a roller crease was attached to the center of the tube. In this tube, 600mmH ₂ O
, run tap water and use a roller cleanser.
Adjust the flow rate to approximately 5 ml/min, and set the flow rate at the beginning of the flow to Q _0.
Flow rate Q ₁ after 30 minutes was measured to evaluate constant flow performance. The results are shown in Table 3.

[Table] From the results in Table 3, it can be seen that the tube of the present invention has extremely excellent flexibility and low-temperature properties. Furthermore, apart from these, ethylene oxide gas sterilization was performed, and the residual amount of ethylene oxide after sterilization was measured by gas chromatography. The results are shown in Table 4. In addition, γ-ray sterilization was performed, and the rate of change in the above △PH after sterilization, permanganate consumption test value (△KMnO ₄ )
The rate of change in Shore D hardness and the amount of change in Shore D hardness were measured. The results are shown in Table 4.

[Table] From the results shown in Table 4, it can be seen that the tube of the present invention has extremely high compatibility or resistance to ethylene oxide gas and gamma ray sterilization partners. In this case, in particular, the residual amount of ethylene oxide and the change in ΔPH after γ-ray sterilization show much better results than when chlorinated polyethylene is used alone. Note that, unlike the present invention, JP-A-56-23959 describes a chlorinated polyethylene tube containing additives. However, when the tube of Example 1 described in the same publication was stored under high temperature and high humidity, the tube changed color. In contrast, in the case of the present invention, there was no change in absorbance at all. In addition, Example 1 of the same publication contains 100 parts by weight of chlorinated polyethylene (polyethylene molecular weight 160,000 and 30,000, chlorine content 34%), 2 parts by weight of calcium stearate and zinc stearate, 0.15 parts by weight of polyethylene wax, and epoxide. It consists of 5 parts by weight of hydrogenated soybean oil. Experimental Example 2 As shown in Table 5 below, the chlorine content of PE-Cl, the type of thermoplastic resin, and the blending ratio were changed, and tubes with different initial elastic moduli were prepared in the same manner as in Experimental Example 1. , was manufactured with the same dimensions as that. Table 5 shows the characteristics of each of these tubes. The number average molecular weight of PE-Cl used was 100,000~
It was set at around 300,000. Moreover, the thermoplastic resin used is as follows. SBS: As in Experimental Example 1 above EVA: VA content 25wt%, density 0.95 Melt index 2g/10 min, average molecular weight approximately 100,000 LLDPE; Density 0.92 Melt index 4
g/10 min SBR; Styrene amount approx. 30 wt% Mooney viscosity 40 SB; Density 0.94 Melt index 2.6 g/10
In addition, for each tube, △(KMnO ₄ ), △PH
In addition, the test results after ethylene oxide gas and γ-ray sterilization were almost the same as in Example 1.

[Table] From the results shown in Table 5, the chlorine content of chlorinated polyethylene is 25 to 45%, and the initial elastic modulus is 5.
It can be seen that when it is less than Kg/mm ² , extremely excellent flexibility and low-temperature properties are exhibited.

Claims (1)

[Scope of Claims] 1. Chlorinated polyethylene with a chlorine content of 25 to 45% by weight, low density polyethylene, styrene-butadiene random copolymer, styrene-butadiene block copolymer, styrene-butadiene teleblock copolymer Combined and vinyl acetate content 30wt%
A medical tube formed by molding a blended polymer with at least one thermoplastic resin selected from the following ethylene-vinyl acetate copolymers into a tubular shape, comprising 10 to 50 parts by weight of the above per 100 parts by weight of chlorinated polyethylene. Contains thermoplastic resin, contains virtually no additives, and has an initial elastic modulus of 5Kg/mm ²
A medical tube characterized in that the curvature at which a bend occurs does not change at 0° C. compared to room temperature. 2. The medical tube according to claim 1, wherein the thermoplastic resin has a refractive index of 1.48 to 1.52. 3 The absorbance of the tube at 500nm is 1mm
2. The medical tube according to claim 1 or 2, wherein the average diameter is 0.18 to 0.65. 4. The medical tube according to any one of claims 1 to 3, wherein the tube has an inner diameter of 1 to 20 mm.